Lifting-jack



"W. N. HARSEN.

'LIFT|NG JACK.

APPLLCATION FILED JAN-20- 1921.

Patented Nov. 1, 1921.

2 SHEETS-SHEET 1.

' INVENTOR. Wane Nffizam W4 ATTORNEY.

- WILLIAM N. VI-IARSEN', or ATTICA, rvircnreen, Assi'enon or one-T tian To 'H E PALMER AND omrrnmnro LEWIS T. nnnms; BOTH or'rrsLAY CITY, MICHIGAN.

LIFTING-JAGK.

T 0 all whom may concern Be it known that I, WILLIAMN. HARsEN,

a citizen of the United States, residing at Attica in the countyiof Lapeer and State of Michigan, haveyinventeds'a new and useful Lifting-Jack, of which the following is a specification: I This invention relates to lifting jacks, and more particularly to doubleacting lifting jacks such as; are adapted to effect a movement of the load both upon the upstroke and down-stroke of the actuatinglever; The invention may be considered as an improvement upon the construction disclosed in my co-pending: application Serial Number 385768, filed June 1', 1920i 7 Said improvement consists, inivarious' structural features which are hereinafter fully described and are illustrated in the accompanying drawing, wherein:

Figure 1 is a view of the improved jack' in side elevation, the two limiting positions between whichthe lever is rocked for raising the load being shown respectively in full lines and dash lines.

Fig. 2 is a similar view of the upper por tion of the jack, showing the positions of the parts resulting from swinging the lever from the raised position shown in full lines in Fig. 1 to the lower limiting position.

Fig.- 3 is ,a cross-section taken-upon the line 3--3 of Fig. 1; "a: Y I

Fig. 4 is a similar view of the invention, showing in full lines the-lower limiting position of the lever and corresponding positions of the parts when the load is being lowered, the other limiting-positionfor lowering the load being indicated in' dash lines. r i

.Fig. 5'is a fragmentary side view of the jack showing the position of the'pa'rts corresponding to the raised position of the In these views the reference character designates the base ofthe standard or frame of the ack, 2 a pair of spaced parallel plates forming the sides of said standard, and3 frame members interposed between the 0p- '7 Specification of Letters :Patent.

ratenteti set. i, 1921.

' Application 'filed 1mm 20,1921. Serial Nb. 433,727.

posed vertical margins of the plates 2. Thus said standard" has a-rectangular tubular form, adaptingfitto house and-guide a vertically actuab'le plunger memberformed by. a palr'of opposed spaced rack bars 4, ntegrally connected at top and bottom and integrallyformed with a surmounted work table or platform 5. The teeth on each rack bar occupy an intermediate relation to the teeth of the opposed rack, the advantage of this arrangement :being presently made clear. For actuating said plunger member vertically there is provided a lever compris mg a pa r of bars 6 extending respectively atopposlte sides ofthe standard and pivoted upon a bolt mounted in the upper portlolis of the plates 2 and passing between the two rackibars. In order to compound lever. Upon the bars 6there are pivoted at 14 two pawls l5iand 16 of inverted U shape, one at'each side of'thefulcrum bolt 7 the horizontal upper portions 17 of said pawls b6111 engageable; respectively with the two'rac 1 bars. Exteriorly upon one of the plates 2 there is pivoted a pair of depending divergenthtrigger members 18, the

pivot pin 19 for said members being positioned slightly above the fulcrum bolt 7-so that said members straddle said bolt. leaf spring 20 issaddled upon the bolt 7 with its extremities bearing upon the ends of the two trigger members to maintain the;

desired divergence thereof. Adjacent their pivotal endsv the pawls 15 and 16 have V- shaped cam projections '21 upon their-opposed edges for engagement by said trigger members. Also the edges of said trigger members'which engage said pawls have por- I r tions meeting. at an obtuse angle to co-act' with said cams; Intermediate their ends the pawls 15 and 16 are formed upon their opposed edges with rounded cam projections 22 which, under certain conditions presently to be explained, co-act' with a roller 23 journaled upon one of the plates 2 between the upper portions of said pawls.

Considering now the operation of the described invention, it is first to be understood that each swing of the handle 13, both upwardly and downwardly, is effected in shifting the load, the latter being raised when the movement of the handle is between the limits shown in Fig. 1,'respectively in full lines and in dash lines, and being lowered when the angle of movement is between the wider limits, illustrated in Figs. 4; and 5. During actuation of the handle 13 from its upper limiting position shown-in fulllines in Fig. 1 to its lower limiting position, shown in dash lines in said figure, the plunger 4. and table .5 are raised from the position shown in Fig. 1 to that disclosed in Fig. 2. During this movement of the handle the pawl .16 is caused to rockon its pivots 14 due to the portion 17 of said pawl riding down the incline of one of the teeth of the engaged rack 4. Also during said movement of the handle the pawl 15 acts to raise the plunger 4 and the load thereupon. While the pawl 16 is being lowered the out-thrust exerted thereupon by the spring 20 acting through trigger 18 maintains said pawl firmly pressed against the corresponding rack, so that after having having ridden down the entire incline of the engaged. tooth the .pawl snaps into position below said tooth, as shown in Fig. 2. Similarly on the upstroke of the handle 13 the pawl 16 will raise the load and the pawl 15 will ride down a tooth of the corresponding rack and firmly engage therebeneath.

Vhen it is desired to lower the load the handle 13 is first swung to one of its extreme positions, as for example that shown in Fig. 1. In this position the cam projection 21 of the pawl 16 engages the trigger member 18" somewhat below the angle of the latter, so that the spring pressure is transmitted through said trigger member to the pawl at a considerable downward inclination. Under such conditions the pawl swings clear of the engaged rack 4 due to its own weight and.

rests, as shown'in Fig. 4, against the roller 23. When the handle 13 is now raised to its other limiting position, shown in Fig. 5, said pawl; clears the tooth ofthe rack 4' which it had engaged, and permits the other pawl, 15, to lower the load. After clearing the rack tooth which it had previously engaged,

, the pawl 16 is swung outwardly to engage the next lilgher tooth due to the cam pro-' jection 22 of'said pawl encountering the roller 23. The continued upstroke of the handle 13, to bring the latter to its extreme upper position shown in Fig. 5, will effect a slight raising of the load through said pawl 16, but a considerably greater lowering of the load will occur during the subsequent down-stroke. On said down-stroke the 193d will be carried by the pawl 16 while the pawl 15, due toits own weight, will incline clear of the associated rack, resting against the roller 23.

Thus it is seen that in the use of the described jack no manipulation or adjustment of the parts is necessary to change the operation from raising of the load to lowering thereof, or vice versa, this result being derived merely from a change in the angle through which the lever is swung.

Furthermore the construction is simple and its parts, being largely adapted to be formed as stampings from sheet material,

may be produced at a relatively low cost. hat I claim is i 1 1. A lifting-jack comprising a frame, a load carrying member vertically adjustable upon said frame, a pair of racks arranged in opposed spaced relation upon said loadcarrying member, a lever pivoted upon said frame for actuating the load-carrying member vertically, pawls carried by said lever respectively engageable with said racks, a pair of divergent trigger members arranged between the pivotal ends of said pawls, and

bearing thereupon, and a spring interposed between said trigger members and acting through the same upon the pawls to urge the same into engagement with their respective between the pivotal ends of said pawls, and

bearing thereupon, and axspring interposed between said trlgger member and acting through the same upon the pawls to urge the same into engagement with their respective racks, said pawls being respectlvely actuable of their own weight clear of the raclrsin.

certain limiting positions 'of said lever, and

being maintained by said spring in engagement with the racks when the'lever ated within narrower limits.

3. A lifting jack comprising a frame,a load-carrying member vertically adjustable upon said frame, a pair of racks arranged in opposed spaced relation upon said loadcarrying member, a leverv pivoted upon said frame for actuating the load-carrying memis operber vertically, pawls carried by said lever- I respectively engageable with said racks,'a

pair of divergent trigger members arranged between the pivotal ends'ofsaid pawls, and bearing thereupon, a spring interposed between said trigger members and acting through the same upon the pawls to urge the same into engagement with fiheirrespective racks, said pawls having opposed cam upon the frame of the jack engaged by the projections and being actuable of their own pawls whenthe latter are clear of the racks weight clear of the engaged racks in certain and acting upon said cam projections to 10 limiting positions of the lever, and being swing the pawls outward,

- maintained by said spring in engagement In testimony whereof I sign this specifiwith the racks when the lever is operated cation. within narrower limits, and a projection WILLIAM N. HARSEN. 

